This invention relates generally to an electrostatographic printing machine and more particularly concerns an improved toner dispensing apparatus for use therein.
The art of electrostatographic printing includes both electrographic printing and electrophotographic printing. In both of the foregoing processes, a latent image, which corresponds to an original document being reproduced, is recorded. Electrophotography achieves this by charging a conductive member to a substantially uniform potential. The charged photoconductive member is exposed to a light image of the original document. As a consequence of this exposure, the charge is selectively dissipated in the irradiated areas in accordance with the light intensity reaching the photoconductive member. This records an electrostatic latent image corresponding to the informational areas contained within the original document. Electrographic differs from electrophotographic printing only in that the latent image is created without the use of a photoconductive member. Hence, the process of electrophotographic printing requires the use of a suitable photoconductor whereas electrography does not.
In both electrophotography and electrography, the latent image is developed by contacting it with a developer mix. Generally, a suitable developer mix comprises dyed or colored thermoplastic particles, known in the art as toner particles, mixed with carrier granules, such as ferromagnetic granules. The toner particles and the carrier granules are triboelectrically attracted to one another with the toner particles adhering to the outer surface of the carrier granules. As the developer mix contacts the latent image, the greater attractive force of the latent image causes the toner particles to transfer thereto from the carrier granules. The toner particles adhere to the latent image in image configuration.
It is evident that during the development cycle, toner particles are depleted from the developer mix. Thus, additional toner particles must be furnished subsequently to the developer mix so as to maintain copy density at a substantially optimum level. It is apparent that in order to produce an efficient printing machine, it is necessary to conveniently and effectively replenish the toner particles used in the formation of copies.
It is a primary object of the present invention to improve toner particle dispensing by advancing the toner particles across the development system uniformly in a gentle manner.